A. Field of the Invention
This invention relates to the field of computerized techniques for orthodontic treatment planning for human patients. More particularly, the invention is directed to a method and apparatus for checking if a target virtual orthodontic arch wire can be inserted into virtual brackets placed on the virtual malocclusion dentition of a patient without conflicts. Additionally, the invention discloses a process whereby the target orthodontic virtual arch wire can be redesigned in case of insertion conflicts.
B. Description of Related Art
In orthodontics, a patient suffering from a malocclusion is treated by affixing brackets to the surface of the teeth and installing an arch wire in the slots of the brackets. The arch wire and brackets are designed to generate a customized force system that applies forces to teeth, by which individual teeth are moved relative to surrounding anatomical structures into a desired occlusion. There are two basic approaches to designing an appropriate force system for a patient. One is based on a straight arch wire and customized brackets, e.g., Andreiko et al., U.S. Pat. No. 5,447,432. The other is based on off-the shelf brackets and designing a customized arch wire that has complex bends and twists designed to move or rotate the teeth in the desired direction. Traditionally, the latter approach has required manual bending of the arch wire by the orthodontist.
In recent years, computer-based approaches have been proposed for aiding orthodontists in their practice. However, these approaches are limited to diagnosis and treatment planning of craniofacial structures, including the straightening of teeth. For example, U.S. Pat. No. 6,648,640 to Rubbert, et al. describes an interactive, computer based orthodontist treatment planning, appliance design and appliance manufacturing. A scanner is described which acquires images of the dentition, which are converted to three-dimensional frames of data. The data from the several frames are registered to each other to provide a complete three-dimensional virtual model of the dentition. Individual tooth objects are obtained from the virtual model. A computer-interactive software program provides for treatment planning, diagnosis and appliance design from the virtual tooth models. A desired occlusion for the patient is obtained from the treatment planning software. The virtual model of the desired occlusion and the virtual model of the original dentition provide a base of information for custom manufacture of an orthodontic appliance. A variety of possible appliance and appliance manufacturing systems are contemplated, including customized arch wires and customized devices for placement of off-the shelf brackets on the patient's dentition for housing the arch wires, and removable orthodontic appliances.
U.S. Pat. No. 6,632,089 to Rubbert, et al. describes an interactive, software-based treatment planning method to correct a malocclusion. The method can be performed on an orthodontic workstation in a clinic or at a remote location such as a lab or precision appliance-manufacturing center. The workstation stores a virtual three-dimensional model of the dentition of a patient and patient records. The virtual model is manipulated by the user to define a target situation for the patient, including a target arch-form and individual tooth positions in the arch-form. Parameters for an orthodontic appliance, such as the location of orthodontic brackets and resulting shape of an orthodontic arch wire, are obtained from the simulation of tooth movement to the target situation and the placement position of virtual brackets. The treatment planning can also be executed remotely by a precision appliance service center having access to the virtual model of the dentition. In the latter situation, the proposed treatment plan is sent to the clinic for review, and modification or approval by the orthodontist. The method is suitable for other orthodontic appliance systems, including removable appliances such as transparent aligning trays.
Machines for bending orthodontic arch wires have been proposed in the prior art. Andreiko et al. describes an apparatus that takes a straight arch wire and imparts a simple planar arcuate curvature to the wire. The wire is customized in the sense that the shape of the arc is designed for a particular patient, but the wire bending apparatus described in Andreiko et al. is limited to a customized bracket approach to orthodontics. In particular, the Andreiko et al. wire bending apparatus cannot produce any complex bends and twists in the wire, e.g., bends requiring a combination of translation and rotational motion.
U.S. Pat. No. 6,612,143 to Butscher, et al. describes a robot and method for automatically bending orthodontic arch wires, retainers, or other orthodontic or medical devices into a particular shape. In particular, the disclosure enables the manufacture of custom, highly accurate orthodontic arch wires. Such wires are ideally suited to an arch wire-based orthodontic treatment regime based on standard, off-the-shelf brackets.
If a customized arch wire cannot be properly inserted into the brackets on the dentition of the patient in the malocclusion state, then its effectiveness may be diminished or lost; and in some instances, the arch wire may have to be discarded and a new one may have to be designed. This is likely to increase the treatment time and cost. The art is lacking in tools that would enable a practitioner in checking if a target virtual orthodontic arch wire can be inserted into virtual brackets placed on the virtual malocclusion dentition of a patient without conflicts in advance of actually placing the real arch wire in the real brackets placed on the dentition of the patient.
The present invention addresses this deficiency in the art and offers a method and apparatus for checking if a target virtual orthodontic arch wire can be inserted into virtual brackets placed on the virtual malocclusion dentition of a patient without conflicts prior to actually manufacturing the arch wire. Additionally, the invention discloses a process whereby the target virtual orthodontic arch wire can be redesigned in case of insertion conflicts.